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rewrite CMYK to RGB conversion

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This commit is contained in:
Andreas Gal 2012-01-29 11:09:33 -08:00
parent 5841383d97
commit 28f82e3dd7
1 changed files with 9 additions and 48 deletions
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57
src/colorspace.js
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@ -369,55 +369,16 @@ var DeviceCmykCS = (function DeviceCmykCSClosure() {
DeviceCmykCS.prototype = {
getRgb: function cmykcs_getRgb(color) {
var c = color[0], m = color[1], y = color[2], k = color[3];
var c1 = 1 - c, m1 = 1 - m, y1 = 1 - y, k1 = 1 - k;
var x, r, g, b;
// this is a matrix multiplication, unrolled for performance
// code is taken from the poppler implementation
x = c1 * m1 * y1 * k1; // 0 0 0 0
r = g = b = x;
x = c1 * m1 * y1 * k; // 0 0 0 1
r += 0.1373 * x;
g += 0.1216 * x;
b += 0.1255 * x;
x = c1 * m1 * y * k1; // 0 0 1 0
r += x;
g += 0.9490 * x;
x = c1 * m1 * y * k; // 0 0 1 1
r += 0.1098 * x;
g += 0.1020 * x;
x = c1 * m * y1 * k1; // 0 1 0 0
r += 0.9255 * x;
b += 0.5490 * x;
x = c1 * m * y1 * k; // 0 1 0 1
r += 0.1412 * x;
x = c1 * m * y * k1; // 0 1 1 0
r += 0.9294 * x;
g += 0.1098 * x;
b += 0.1412 * x;
x = c1 * m * y * k; // 0 1 1 1
r += 0.1333 * x;
x = c * m1 * y1 * k1; // 1 0 0 0
g += 0.6784 * x;
b += 0.9373 * x;
x = c * m1 * y1 * k; // 1 0 0 1
g += 0.0588 * x;
b += 0.1412 * x;
x = c * m1 * y * k1; // 1 0 1 0
g += 0.6510 * x;
b += 0.3137 * x;
x = c * m1 * y * k; // 1 0 1 1
g += 0.0745 * x;
x = c * m * y1 * k1; // 1 1 0 0
r += 0.1804 * x;
g += 0.1922 * x;
b += 0.5725 * x;
x = c * m * y1 * k; // 1 1 0 1
b += 0.0078 * x;
x = c * m * y * k1; // 1 1 1 0
r += 0.2118 * x;
g += 0.2119 * x;
b += 0.2235 * x;
// CMYK -> CMY: http://www.easyrgb.com/index.php?X=MATH&H=14#text14
c = (c * (1-k) + k);
m = (m * (1-k) + k);
y = (y * (1-k) + k);
// CMY -> RGB: http://www.easyrgb.com/index.php?X=MATH&H=12#text12
r = (1-c);
g = (1-m);
b = (1-y);
return [r, g, b];
},